One type of conventional book trucks has swingably mounted thereon a plurality of shelves each of which is resiliently held in a slanted condition and adapted to swing down to a horizontal position.
In order to load the continuously conveyed tire tread members onto such shelves of the book truck, an operator heretofore performed such an operation as lining up and piling the tread members on a horizontal uppermost shelf and then swinging down an immediately upper slanted shelf to be kept in a horizontal condition for repeating the same operation as such. The loading operations were required to be repeated for all the shelves, which were simple and but time consuming, resulting in laborious and repetitive work for the operator. It was thus impossible for the operator to continuously perform such operations in view of his physical and mental aspects so that the loading operations were alternately carried out by two or more operators. On the other hand, the tread member was apt to be deformed during handling by the operator with the result that a finished tire was undersirably affected as regards such tire characteristics as unbalance property, uniformity property and the like.